[Numpy-discussion] Controlling endianness of ndarray.tofile()
Hi, On my system (Intel Xeon, Windows 7 64-bit), ndarray.tofile() outputs in little-endian. This is a bit inconvenient, since everything else I do is in big-endian. Unfortunately, scipy.io.write_arrray() is deprecated, and I can't find any other routines that write pure raw binary. Are there any other options, or perhaps could tofile() be modified to allow control over endianness? Cheers, Ben -- Benjamin D. Forbes School of Physics The University of Melbourne Parkville, VIC 3010, Australia ___ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion
Re: [Numpy-discussion] Controlling endianness of ndarray.tofile()
Hi Ben,
based on this example
https://bitbucket.org/lannybroo/numpyio/src/a6191c989804/numpyIO.py
I suspect the way to do it is with numpy.byteswap() and numpy.tofile()
From
http://docs.scipy.org/doc/numpy/reference/generated/numpy.ndarray.byteswap.html
we can do
A = np.array([1, 256, 8755], dtype=np.int16)
map(hex, A)
['0x1', '0x100', '0x2233']
A.tofile('a_little.bin')
A.byteswap(True)
array([ 256, 1, 13090], dtype=int16)
map(hex, A)
['0x100', '0x1', '0x3322']
A.tofile('a_big.bin')
Gary
On Tue, Jun 21, 2011 at 6:22 PM, Ben Forbes bdfor...@gmail.com wrote:
Hi,
On my system (Intel Xeon, Windows 7 64-bit), ndarray.tofile() outputs
in little-endian. This is a bit inconvenient, since everything else I
do is in big-endian. Unfortunately, scipy.io.write_arrray() is
deprecated, and I can't find any other routines that write pure raw
binary. Are there any other options, or perhaps could tofile() be
modified to allow control over endianness?
Cheers,
Ben
--
Benjamin D. Forbes
School of Physics
The University of Melbourne
Parkville, VIC 3010, Australia
___
NumPy-Discussion mailing list
NumPy-Discussion@scipy.org
http://mail.scipy.org/mailman/listinfo/numpy-discussion
___
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Re: [Numpy-discussion] Controlling endianness of ndarray.tofile()
Thanks Gary, that works. Out of interest I timed it:
http://pastebin.com/HA4Qn9Ge
On average the swapping incurred a 0.04 second penalty (compared with
1.5 second total run time) for a 4096x4096 array of 64-bit reals. So
there is no real penalty.
Cheers,
Ben
On Tue, Jun 21, 2011 at 8:37 PM, gary ruben gru...@bigpond.net.au wrote:
Hi Ben,
based on this example
https://bitbucket.org/lannybroo/numpyio/src/a6191c989804/numpyIO.py
I suspect the way to do it is with numpy.byteswap() and numpy.tofile()
From
http://docs.scipy.org/doc/numpy/reference/generated/numpy.ndarray.byteswap.html
we can do
A = np.array([1, 256, 8755], dtype=np.int16)
map(hex, A)
['0x1', '0x100', '0x2233']
A.tofile('a_little.bin')
A.byteswap(True)
array([ 256, 1, 13090], dtype=int16)
map(hex, A)
['0x100', '0x1', '0x3322']
A.tofile('a_big.bin')
Gary
On Tue, Jun 21, 2011 at 6:22 PM, Ben Forbes bdfor...@gmail.com wrote:
Hi,
On my system (Intel Xeon, Windows 7 64-bit), ndarray.tofile() outputs
in little-endian. This is a bit inconvenient, since everything else I
do is in big-endian. Unfortunately, scipy.io.write_arrray() is
deprecated, and I can't find any other routines that write pure raw
binary. Are there any other options, or perhaps could tofile() be
modified to allow control over endianness?
Cheers,
Ben
--
Benjamin D. Forbes
School of Physics
The University of Melbourne
Parkville, VIC 3010, Australia
___
NumPy-Discussion mailing list
NumPy-Discussion@scipy.org
http://mail.scipy.org/mailman/listinfo/numpy-discussion
___
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http://mail.scipy.org/mailman/listinfo/numpy-discussion
--
Benjamin D. Forbes
School of Physics
The University of Melbourne
Parkville, VIC 3010, Australia
___
NumPy-Discussion mailing list
NumPy-Discussion@scipy.org
http://mail.scipy.org/mailman/listinfo/numpy-discussion
